One manner of reducing anthropogenic carbon-dioxide (CO2) emissions into the atmosphere is the sequestration of the CO2 in porous, brine-filled formations having cap rocks. The CO2 is introduced into the suitable formation, typically at a depth of between one and three kilometers via a borehole drilled in the formation. There the CO2 is positively buoyant and rises until it encounters a cap rock, beneath which it spreads primarily horizontally. The separate-phase CO2 gradually dissolves into the underlying brine. Initially this occurs by diffusion. However, CO2-enriched brine is denser than pure brine and the layer may eventually become gravitationally unstable and experience convective overturning. Understanding the dissolution process is of practical interest as it can be important in determining various parameters such as the capacity of the formation to receive the CO2, the rate at which the CO2 may be injected into the formation, and the manner in which and locations to which the CO2 spreads over time.
Before undertaking a sequestration project, it is common to attempt to model the project. Geological models are known. For example, ECLIPSE (a trademark of Schlumberger) is an oil and gas reservoir simulator that provides a high resolution geological model with a grid scale of approximately 1 cm for simulating flow and mass transport in highly complex, variably saturated conditions. ECLIPSE, which is described in co-owned U.S. Pat. Nos. 6,018,497, 6,078,869, and 6,106,561 which are hereby incorporated herein in their entireties, can incorporate density effects when modeling brine as well as coupling geomechanical modeling with fluid flow. ECLIPSE can also perform fluid flow predictions. However, neither ECLIPSE, nor other presently available geological models can computationally account for solutal convection over a portion of a formation that may have a horizontal breadth on the order of kilometers.